[alsa-devel] Using MMAP feature

Hello,

I'm going to use the MMAP feature of ALSA. I understood I have to use snd_pcm_mmap_begin and snd_pcm_mmap_commit functions, but I can't understand the meaning of some parameters in the snd_pcm_mmap_begin function: when I call this function in order to have access to the capture stream on a call like this:

err = snd_pcm_mmap_begin(capture, &c_area, &c_offset, &c_frames);

it keeps to return c_frames = 0: is it right ? what does this mean? is the buffer full so that I can read samples or the available contiguous space to be read is 0?

Thank you,

Alberto